1. Field of the Invention
This invention relates to an improvement on a camera of the kind having a focal length variable photo-taking optical system.
2. Description of the Related Art
Referring to FIG. 1 of the accompanying drawings, in a focal length variable optical system such as a zoom lens mounted on a camera, in general, a variator 1 and compensator 2 are arranged to be shiftable in the direction of an optical axis with rollers 1a and 2a, which are provided on the variator 1 and the compensator 2, guided by a straight moving slot 3a provided in a straight moving barrel. The rollers 1a and 2a are fitted in zooming cam grooves 4a and 4b of a cam ring 4 which is arranged to rotate on the optical axis. A zooming operation is thus arranged to be performed with the variator 1 and the compensator 2 shifted to predetermined positions according as the cam ring 4 rotates. The illustration includes a focusing lens 5.
The zoom lens of this kind is arranged to have a plurality of lenses movable relative to each other. Therefore, the zoom lens is generally larger than an ordinary photo-taking lens. With such a zoom lens incorporated in a camera, the thickness of the camera increases in the direction of the optical axis of the lens. This greatly impairs the portability of the camera.